Abstract

Background

Anaemia may increase risk of dementia or cognitive decline. There is also evidence
that high haemoglobin levels increase risk of stroke, and consequently possible cognitive
impairment. The elderly are more at risk of developing dementia and are also more
likely to suffer from anaemia, although there is relatively little longitudinal literature
addressing this association.

Methods

To evaluate the evidence for any relationship between incident cognitive decline or
dementia in the elderly and anaemia or haemoglobin level, we conducted a systematic
review and meta-analyses of peer reviewed publications. Medline, Embase and PsychInfo
were searched for English language publications between 1996 and 2006. Criteria for
inclusion were longitudinal studies of subjects aged ≥65, with primary outcomes of
incident dementia or cognitive decline. Other designs were excluded.

Results

Three papers were identified and only two were able to be combined into a meta-analysis.
The pooled hazard ratio for these two studies was 1.94 (95 percent confidence intervals
of 1.32–2.87) showing a significantly increased risk of incident dementia with anaemia.
It was not possible to investigate the effect of higher levels of haemoglobin.

Conclusion

Anaemia is one factor to bear in mind when evaluating risk of incident dementia. However,
there are few data available and the studies were methodologically varied so a cautionary
note needs to be sounded and our primary recommendation is that further robust research
be carried out.